[Standards] mobile optimizations (was: Re: Google Andro ï d SDK not XMPP compliant ?)

Fabio Forno fabio.forno at gmail.com
Thu Feb 14 23:43:23 UTC 2008


On Fri, Feb 15, 2008 at 12:10 AM, Boyd Fletcher
<boyd.fletcher at je.jfcom.mil> wrote:

>  I agree that protocol improvements are in order. But XMPP data was looked
> at but some of the folks on the W3 committee as example data and the
> compression was significant. There has also been some internal testing in
> DOD using EfficientXML with captured XMPP data streams and we have seen a
> decrease in size of 4-5 times compared to zip lib approach.

Just to setup the correct benchmark: you mean EfficientXML +
compression or EfficientXML alone? (I promise on the weekend I try to
get some figures out, but without compression it's difficult to
believe you can get those improvements)

>  I strongly disagree. we have using binary XML for years and the libraries
> are quite stable and reliable. Unfortunately there just aren't very many
> open source libraries.

Indeed that was I meant, sorry for not being clear.

> Hopefully that will change over the next 2 years as
> W3C's EXI specification is ratified.

That was the other point about the maturity, I should have used
"consensus": though having some libs, it is very difficult to base
some extension of xmpp on a not ratified standard and choose between
the many xml binding options. If the situation changes (or has
changed) I'd be happy to jump again on the binary supporters side,
where I was before trying to implement it for j2me ;)

>  In very high production environments, hundred of thousands of
> users/connections the difference in binary XML vs. regular XML can be
> significant not just in reduced bandwidth utilization but also in reduced
> CPU overview in processing the XML data.
>
>  A couple of years ago, one of the large stock exchanges tried to switch to
> XML as the data transport. It tanked because the servers could not process
> the XML fast enough to keep up with the transaction rate. They switched back
> to their legacy binary protocol within 2 days.

I don't have troubles in believing this, but the scenario - I guess -
is slightly different, since I don't think that their format had many
extensibility features (when the grammar is not fixed you loose most
of the possible optimizations)

-- 
Fabio Forno, Ph.D.
Bluendo srl http://www.bluendo.com
jabber id: ff at jabber.bluendo.com



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